The present disclosure relates to a gearwheel transmission having at least one gearwheel stage in which at least one of the gearwheels is fastened coaxially on a hollow shaft which is rotatably mounted in a transmission housing by means of at least two shaft bearings. The disclosure also relates to a wind power plant which comprises a gearwheel transmission of said type.
The preferred field of use of the present disclosure is wind power plant technology. In particular in the case of wind power plants of relatively high power, that is to say above approximately 1.5 megawatts, use is generally made of extremely large gearwheel transmissions in order to step up a low rotational speed of a rotor which is impinged on by wind, such that an electric generator for generating electrical energy can be driven at a suitable higher rotational speed. Furthermore, gearwheel transmissions of the type of interest here may also be used in other technical fields, such as marine technology, motor vehicle technology and the like, preferably where large transmissions of the above-specified higher power classes are concerned.
DE 34 23 993 A1 concerns a large transmission of the type of interest here, which is formed with a plurality of gearwheel stages. Said gearwheel transmission is designed as a multi-way transmission with power splitting and comprises an adjustable pinion arrangement for power distribution between a plurality of power paths, which pinion arrangement, in the manner of a planetary gear set, is connected upstream of a further load distributor device such that two or more coaxially arranged pinions with defined power division may be provided. The number of power branches is multiplied according to the number of pinions. This results in an extremely compact transmission of high power density. This design principle entails the use of hollow shafts, through the inner duct of which further shafts are guided in this case. The hollow shaft is provided, radially at the outside, with a gearwheel in order to transmit the power flow onward by means of a spur gear pairing. Here, however, said gearwheel is always a pinion.
DE 27 39 596 A1 discloses another gearwheel transmission in which not the pinion but rather the larger gearwheel which meshes with said pinion is arranged on hollow shafts. In specific terms, two large gears which are connected to the drive output shaft of the gearwheel transmission are arranged on hollow shafts which are in alignment with one another and which are mounted in each case separately in the transmission housing. Those ends of the two coaxial hollow shafts which face toward one another are connected to the drive output shaft via toothed couplings. Each hollow shaft is rotatably mounted in the valve housing by means of two shaft bearings arranged on each end side. Each hollow shaft has a tubular diameter which remains constant in principle, and the respectively associated large gearwheels have a toothing diameter which is a multiple of the shaft diameter. These geometric relationships result in extremely massive gearwheels which must be manufactured from a high-grade toothing material in order to be able to withstand the loadings during operation. In contrast, the associated hollow shafts are generally produced from a tempering steel.
Such massive gearwheels disadvantageously result in an extremely high overall weight of a gearwheel transmission equipped with said gearwheels.
Furthermore, a hollow shaft produced from relatively high-grade steel such as tempering steel has the disadvantage of a cumbersome material with corresponding heat treatment and subsequent elaborate machining.